Hybrids not so green

SIR — Alexander Parker’s review of the Mercedes-Benz hybrid SUV (Clever big Benz hybrid makes the greens see red, August 4) would have us believe that “for us in SA, plug-in hybrids are the solution to environmental concerns about running cars”.

Nonsense! For us in SA, hybrids are tantamount to running our cars on coal. Our hybrid cars run on fuel dug from the ground, transported by road in 40-tonne side-tipper trucks, burnt and converted to electricity at perhaps 40% efficiency. Then it is sent hundreds of kilometres along obtrusive transmission lines and local distribution lines before reaching our homes. By then, a further 10% has been lost.

Our fuel is then stored in a lead acid battery (itself polluting in manufacture and disposal). That fuel then drives a motor, which itself is no more efficient than an internal combustion engine. Coal to electricity to wheel efficiency is about 25%, whereas that of oil to petrol to wheel is about 78%.

Our hybrid has two engines and two batteries simply in order to be able to use coal as a power source. How “green” can that be?

Of course, little of that would be true if hybrid owners only ever used dedicated solar voltaic panels and/or wind generators to charge their batteries, rather than Mpumalanga coal. But what happens when the sun doesn’t shine and the wind doesn’t blow? Luckily they also have a petrol engine. Which also demonstrates a further point that “sustainable power” also requires reliable base-load power.

Phil Flockton

Rondebosch